Tag: nanotubos de carbono

Prof. Daniel Ugarte in one of his two favorite activities: cooking. The other one is experimental research.

Daniel Mario Ugarte was born on March 23, 1963 in Cosquín, a small town in the mountains of the province of Córdoba (Argentina). He grew up in a family environment that was very stimulating to curiosity, learning and experimentation. After completing his elementary and secondary education in this city, he studied physics in the province’s capital, at the National University of Cordoba, the oldest in the neighboring country (founded in 1613). After graduation, he completed an internship in transmission electron microscopy at Université Paris-Sud, France, where he ended up doing his doctorate in nanoscience subjects (although at that time the “nano” prefix was not yet widely used). Ugarte received his Ph.D. in physics in 1990. He moved to Switzerland where he completed a post-doctorate internship lasting about three years at the École Polytechnique Fédérale de Lausanne (EPFL). There he continued to do nanoscience and nanotechnology and obtained results with great academic impact, notably the “nano-onions of fullerene”, which earned him, at the age of 29, his first article in the journal Nature, signed by him alone and highlighted in the cover of the issue. This paper, which today has more than 2,000 citations, would be the first of six articles published by Ugarte in the two main scientific journals of the world (Science and Nature), among dozens of publications in specialized scientific journals, also of very high impact, such as Nature Nanotechnology, Nano Letters, Physical Review Letters, among others.

In 1993, for personal reasons, Ugarte went to live in Brazil, and began to work with the team that was beginning the construction of the National Synchrotron Light Laboratory (LNLS) at the current site, in the city of Campinas (São Paulo state). It was in this context that he was able to make real his idea of constructing an electron microscope laboratory for research and training really open to the entire scientific community, including students. The Laboratory of Electronic Microscopy began its activities in 1999, directed by the Cordoban scientist, and was the seed of the current National Nanotechnology Laboratory (LNNano). Between 1994 and 1998, Ugarte also served as visiting professor at EPFL. In 2004, he left LNLS to take up the position of associate professor at the Gleb Wataghin Institute of Physics (IFGW), State University of Campinas (UNICAMP). Since 2007, he is a full professor of this institution. In addition, from 2004 to 2007, Professor Ugarte coordinated a research network on nanomaterials, NANOMAT, which included 23 institutions and 150 researchers.

Throughout his scientific career, Daniel Ugarte has delivered more than 100 invited lectures at international scientific events and received several prestigious awards for his exceptional academic contributions, such as the Prix Latsis Universitaire EPFL (Switzerland, 1994), the John Simon Guggenheim Fellowship (USA, 2002), the Scopus Brazil Award from Elsevier and CAPES (Brazil, 2008) and the Physics Award from The World Academy of Sciences, TWAS (Italy, 2018). In 2012, Ugarte was elected a member of the Brazilian Academy of Sciences (ABC). In addition, several students guided by him received prizes for their PhD theses, granted by the Presidency of the Republic, CAPES, the Brazilian Society of Physics (SBF) and the IFGW – UNICAMP.

Daniel Ugarte is the author of more than 100 articles published in international peer-reviewed journals. According to Google Scholar, his academic production received more than 16,600 citations and his h-index is 43.

Take a look at our interview with this founding member of B-MRS and learn more about his life story, his key findings, his criticisms of some trends in how to make science and his message to younger researchers.

B-MRS Newsletter: – We would like to know how / why you became a scientist. When did the desire to be a scientist come to you?

Daniel Ugarte: – I was born in Argentina, with the genetic information typical of that country: mother of Italian origin, and father of Spanish origin (Basque, to be precise), but trying to be English (I love rugby). I think the example of my parents’ curiosity, work, and varied interests had a majority influence on my choices. I was born and raised in a town in the middle of mountains in Argentina (the town of Cosquín, with approximately 10,000 inhabitants, in the province of Córdoba). My mother was a teacher of elementary school and always tried, with very scarce financial resources, to obtain books to continue studying and improve her classes (at that time there was no internet); we read together these new texts of history, dinosaurs, etc. My father, even though he attended school only until he was 12 years old, was always very curious and active. He did everything as an amateur and self-taught; very active, he was an actor, a painter, a musician, he repaired everything, made keys etc. Curiosity and childish spirit were always with him: every new thing, he wanted to dismount to see how it worked. If I had to define his profession, I would say that he made publicity posters. In his workshop, all the equipment was built by himself. In that room of constant mess, I played drilling irons, soldering wires, cutting wood, hammering things. We had few luxuries, no expensive toys, but there were always books, and I did very unusual things (supervised by my parents) in the eyes of other children, such as model airplanes, galena radios, a telescope, etc. With my mother, we always cooked new recipes (gnocchi, cakes, alfajores, sweets, etc.); at 10 years old, every Sunday at noon, I prepared the family barbecue. These experiments of chemistry and heat were very instructive (and tasty), flavors and aromas that I still try to reproduce accurately today. Finally, to complete, I was lucky enough to have some ease with logic and mathematics, which was in evidence when I went to school. I have to thank the Science and Mathematics teachers who worked hard to keep my motivation in that little town so that I could grow and develop this incipient talent. I think that with this childhood, the dream of doing science and working in a laboratory (or a kitchen) making discoveries and building wonderful instruments is the most natural consequence of the world (I must clarify that outside the laboratory my main hobby is to cook).

B-MRS Newsletter: – Briefly tell us what led you to work in the field of nanosystems.

Daniel Ugarte: – In fact I arrived in the “nano” world through electron microscopy. At the Universidad Nacional de Córdoba I studied physics, much more interested in the experimental profile and in the laboratory work using the hands. In the course, you must do a final dissertation to obtain your diploma. Among the various options of the Institute of Physics, I preferred to do a project associated with scanning electron microscopy and X-ray spectroscopy. A pragmatic choice aiming at having more employment options after my graduation. At that moment, I was lucky, an opportunity arose to go to France to do an internship in transmission electron microscopy, and after arriving there (Laboratoire de Physique des Solides, Université Paris-Sud, Orsay), I was invited to do a doctoral thesis to study the excitation of surface plasmas in small particles (in English at the time they were “small particles”, not “nanoparticles” as it is today). The term “nano” did not yet exist, and “plasmon” was only a curiosity (today it is one of the most active nanoscience themes). Once I finished my thesis, I was able to get a postdoctoral fellowship in Switzerland, in one of the first institutes to focus on the new properties of particle size reduction (Institut de Physique Experimentale, Ecole Polytechnique Féderale de Lausanne). In short, I started in the nano embryos and always continued to study small systems with high spatial resolution techniques associated with transmission electron microscopy. The atomic or nanometric resolution of this technique is imperative for basic or technological research in nanosystems, and expensive microscopes have become symbols to display the richness of each “nano” program.

B-MRS Newsletter: – What are your main scientific and technological contributions to the Materials area in your own assessment and why do you consider them to be the most relevant?

Daniel Ugarte: – Carbon nanostructures (fullerenes, nanotubes, graphene) represent a typical example of nanomaterials with novel properties. Considering dates, fullerenes were discovered in 1986, the solid of fullerenes in 1990, the nanotubes in 1991. Working in Switzerland in 1992, I accidentally observed that by irradiating carbon materials with the electron beam of a transmission electron microscope, everything turned into “fullerene onions” (concentric graphite spheres, like a Russian doll). This experiment generated a new member for the newly discovered fullerene family, and the work had an incredible repercussion worldwide. However, the interesting thing was that this was not my postdoctoral project, which was a research focused in the study of electronic diffraction of metallic nanoparticles. In Lausanne we had a complete microscopy lab with all the border equipment. And I noticed that no one wore them at night, so I decide to go and play there … to make exploratory, innocent, alternative experiments and, unintentionally, the onions appeared …. But when I first spoke of the results no one believed; a reviewer for the prestigious journal Physical Review Letters said that my data was as ridiculous as cold fusion (a highly controversial subject at that time); that was an insult of the worst level. But I kept defending my job, I got the same results over and over again, and they were the truth. I continued presenting the result in the conferences; I survived many violent and humiliating comments. To make things a bit out of the paradigm one must have “hard leather”. Finally, with the unexpected and spontaneous support of Sir Harry Kroto (who received the Nobel Prize in Chemistry in 1996), who did not know me and never spoke to me, my article was published in the journal Nature. I was less than 30 years old, very innocent, and I was very surprised by the enormous interest of the media; I reported to many countries, among them Japan, Germany, etc. It felt like the world was falling on my head. With naive (unpretentious) and out of context experiments done at night with advanced instruments, I had created work options that knocked on my door. However, at the moment, to the surprise of my French and Swiss colleagues, I took an alternative route, and in 1993 I choose to live in Brazil for personal and family reasons.

A few years later, in 1995, we were on a Saturday afternoon at the laboratory in Lausanne, making brainstorming proposals with my friend Walt de Heer (an incredible scientist considering depth and creativity). We decided to test one that came up there at the time: using carbon nanotubes (the tip is really thin) to produce a source of electrons. We put together a hydraulic press, plumb-type teflon tape, microscope grids, old mica, some lab things (vacuum chamber, oscilloscope, etc.) and set up something awful, dirty, grotesque, completely improvised, and … it worked !!! . The result was published in the journal Science. This experiment created a new area of applied research for the carbon nanotubes that several industrial laboratories tried to explore; until today it is an active area of research. Again, in my way, another innocent experimental proposal, but creative and relaxed (in this case the result was not accidental, but planned), which captured the interest of the international technological community.

In my group in Brazil, I decided to invest in a new line of research based on an irreverent experiment proposed in Spain by a researcher called Costa-Kramer (Nanowire formation in macroscopic metallic contacts: quantum mechanical conductance tapping a table top, Surf. Sci. 1995). If we add two pieces of gold and then separate them, at the end a very thin yarn (as with chewing gum) is formed which may even have an atom of diameter. By measuring the electric current through this wire during elongation, we can study quantum effects in electrical conduction by nanostructures. In Campinas, my student Varlei Rodrigues (who later received the SBF Prize for Best Doctoral Thesis in Physics in 2003) built an instrument specifically designed to carry out this study with high precision in ultra high vacuum (UHV) conditions. Later we were able to make electron microscopic images of the atomic arrangement of the wires generated by mechanical elongation and also theoretical calculations in collaboration with the group of Douglas Galvão. From this information we could understand in detail our experimental measurements; from these results I was invited to give almost a hundred lectures at international conferences. I believe that these results were very important from the Brazilian point of view, since all the research was done in the country: ideas, advanced experiments, construction of specific scientific instrumentation, theoretical calculations and understanding. In addition to the scientific impact, the research on metallic nanowires represents an important achievement, as it allowed us to show, by example, that competitive experimental nanoscience studies can be done in the country, combining work with originality and a certain degree of risk.

Speaking of results feeds our ego (the little Argentine that we all carry inside …); another aspect of our contribution to society comes when our effort is dedicated to community growth, in particular to raise the level of science in the country. In this sense, I would like to recall one of the most comforting works of my career: the idealization and creation of a multi-user electron microscopy laboratory in Campinas. This project had the constant and unconditional support of the LNLS directors at the time (Cylon da Silva, Aldo Craievich and Ricardo Rodrigues). Finally, the microscopes were acquired with resources (many resources !!!) from The São Paulo Research Foundation (FAPESP). From the initial idea, I worked so that the laboratory was open and available to Brazilian researchers (not in intentions, but in reality) and also had the training of human resources as a focus of their activities. Contrary to the general opinion of the community, in the microscopy laboratory all the observations were made by the undergraduate or graduate students involved in the projects, after a training process. Many students learned to work, and the instruments did not break at all, but we had to give ourselves the time to teach the interested researchers. This mode of operation aimed at avoiding the feudal system (“lord of instruments”) or application of psychophanism. I stayed in this lab until 2009. This laboratory grew and became what is now called the National Nanotechnology Laboratory (LNNano).

B-MRS Newsletter: – You have an unusual amount of articles published in high-impact journals (Science, Nature, PRL …), especially in the context of developing countries. To what factors and competences do you attribute this characteristic of your scientific production?

Daniel Ugarte: – In the previous question I tried to give several examples of some important moments of my scientific activity. Workload, much study, and the courage to take risks were essential to make daring and original experiments. But there is one thing I always try to teach my students: if we do a project, he must bring a relevant contribution (if it works …). If any publication is generated, it has to contribute with new knowledge, not of a lie, but of truth. We will not only choose research topics that generate quick results; probably our study will take time, we will have to understand and deepen in a lot of new thing. We may even need to develop tools / software to answer the scientific question. And my students ask: Will it work? I say, I do not know, if I knew it would work out, it would not have any emotion, but I can guarantee that you will grow a lot and get a solid background. For example, in the topic of gold nanowires we had to respond to comments (from a competitor) on what happened to mechanical elongation at low temperature. For this, we needed to perform an extremely challenging experiment and try to observe the mechanical deformation of nanowire in situ inside the microscope at low temperature with atomic resolution using a sample holder in liquid nitrogen. The student who came across the project (Maureen Lagos, who later won the CAPES thesis award in 2012) asked me: Will it be difficult? What do you think? My answer was: I think it will not work, but to answer this to the community we must test if it works or not, go, try to do your best and good luck (you will need a lot …). To my surprise, he got the measurements, very difficult and time consuming; these studies made here in Brazil receive until today (10 years later) many praises and recognition in the scientific community.

Another aspect, other than risk or daring, is quality; every student or colleague who worked with me knows that we always do the best we can, we don´t have “more or less”. Only the best is accepted, or you have to do the experiment again until you get the highest quality. Some students hate me, but recently an alumnus of UNICAMP (now a professor in the United States) published an article in the journal Nature, and sent me a message thanking me, because today he gives great value to what he has learned with me about drawing his limits. To give total quality to all the study content, in the experiments – which are the basis in our group -, in the theoretical study, in the interpretation, in the modeling, etc. As in all professions, we build our reputation over the years, and it may be prestigious or not. It has always been a pride for my group that our colleagues and competitors receive our works with attention, believing that we have done our best for each published result (but they not always agree with our conclusions / interpretations … as everyone we have many articles rejected).

When I was part of the committee that analyzes projects at CNPq, I was surprised by the number of Brazilian researchers who publish more than, say, 50 articles a year, some of them having high administrative or management positions in Brazilian teaching or research institutions, which requires concentrated effort 24 hours a day. Considering my ability to do research, I find it totally impossible to think about producing almost one publication per week !!! And that if I stayed in the lab all day with the students. At this point I would like to return to the concept of quality, considering the number and the scientific contribution of articles generated by a group or researcher. We can assume that it follows a statistical distribution with Gaussian form described by two parameters with a mean and a width (notes from 1 to 10). I know researchers with a little incoherent production, able to do the best (work note 10), and at the same time, the worst (some papers deserve very low grade, say 1-2). Let´s consider a hypothetical group in which the average contribution to knowledge per publication is good / very good (average 6 or 7), and several dozen publications are generated. Statistically, you must publish a high-quality (top-of-the-distribution and far-out-of-the-middle) article that will get community recognition (hopefully, published in a high-impact magazine). But if you make 100 publications a year and none reaches a certain relevance in your area, our simple statistical model indicates that the average contribution of your work should be moderate. In addition, the width of the distribution can also be moderate; in this situation, the production / work is consistent, in a narrow range of quality level. The causes can be varied; in some cases, it is reasonable to associate a moderate contribution to, for example, the researcher’s youth, poor infrastructure or limited funding. The critical point is when the problem is at the root, and the causes of moderate quality are associated with scientific / technical targets of minor importance and low risk. What to expect from an environment where both funding agencies as well as the researchers themselves (not only the agencies’ fault) accept that this serious disability can be fully compensated for by the number of publications? The result will be that the numbers will increase, but the impact will decrease.

Comic strip of Argentine cartoonist Quino sent by Prof. Ugarte to represent some of his criticisms to a way of doing science.

Maybe I’m irresponsible, stubborn (Basque roots help), but my work over the years has followed certain standards. I prefer to make a high-gastronomic dish (sometimes half-burned) than to make hundreds of rice and beans dishes. I prefer to do less things and not have numerous irrelevant publications involving work that did not include any risk (I also have these jobs), and so take the time to update myself, challenge myself, study and see things out of my main interest. So I have the opportunity for new ideas, innocent, irresponsible, that with luck will work. It is important, first, to have clearly in mind what new / different thing we are going to do in our research; if there is nothing new / risky, how will the contribution to the generation of knowledge be? In fact, this line of thinking is not very popular if we look closely at most of the projects funded in the Brazilian community (however, many discourses and plans define it as essential). On the contrary, viability is often more important than relevance and originality. We could also mention other issues that make it difficult to increase the relevance of nanoscience research in Brazil, such as experimental physics, scientific instrumentation, multidisciplinarity, where the contrast between discourse and reality gives great sadness. As in gastronomy, I prefer “slow food”, a good dish, good wine and time to enjoy. We must stand up against “fast science” (short-term projects), as this is leading to shallow-knowledge.

It is sad to see the evolution of Brazil, the numbers grow, the impact decreases … Many can see positively the publication in journals of high impact, but not everyone agrees. Let me give you an example. I decided to study some new subjects where I consider that there are opportunities for very original and interesting things. To ask deeper questions, one must understand. Learning takes time … So, my activity report had problems to be approved for low productivity: I did not reach the average. I have never had much diplomacy or political skills, so joining all my revolt, and being Argentine and Basque at the same time, I wonder: am I terribly inefficient and should I retire, which at least allows me to maintain my spirit, my freedom and form of work intact? There are many discourses on how to stimulate cutting-edge research and train researchers; I think my way of contributing is to work “in my own way” and to give an example to anyone who considers it valid.

I cannot forget to thank CNPq’s Universal system, where I know I can always send crazy ideas, and the review system respects my story and relies on my “irresponsibility”. It’s little money (if compared to international standards), but I get a lot of freedom !!!, and that’s essential to be creative!!!

B-MRS Newsletter: – Now we invite you to leave a message for readers who are starting their scientific careers.

Daniel Ugarte: – Scientific work requires being dreamy and passionate, a lot of effort in study and work. We have to be able to associate knowledge, originality, infrastructure, technical ability, etc. I think it is very important to show young people that it is possible to dream and do cutting-edge research in Brazil. The scientific milieu can be very aggressive, but we must be clear that merit is the most important parameter, and that although the research environment is extremely competitive, it is essential to develop our activities while maintaining the human qualities, professionalism and ethics.

Throughout a scientific career we must face many different situations. My academic life in Brazil had many stages, some were resplendent, with work, challenges, productivity and with excellent and motivated students (the laboratory was paradise). But I also experienced very sad, disappointing stages associated with local mediocracies. However, the stones thrown in our path have been completely overcome by our work, our results and our ethics. Always, always, merit and competence will win in the game of science.

Scanning electron microscopy image of carbon nanotube bundles obtained by the method of the CTNano team.

A team of scientists from institutions in Minas Gerais made a promising contribution to the production of carbon nanotubes. These hollow cylinders, whose carbon walls are only 1 atom thick, are already part of some products (batteries, automotive materials, water filters), but their industrial production is still incipient and needs solutions to lower costs and to increase efficiency, among other challenges.

The Brazilian researchers introduced a novelty in a stage of one of the most consolidated techniques for the mass production of nanotubes, chemical vapor deposition (CVD). As a result, the team was able to produce double- and triple-walled nanotube bundles (somewhat similar to two or three hollow cylinders, one inside the other). Thin, long and of high purity, the nanotubes had diameters of 3 to 8 nanometers, lengths up to 50 thousand times the diameter (from 150 to 300 micrometers) and 90% of carbon in their composition.

“The main contribution of this work is the presentation of a scalable and cost effective process for the synthesis of carbon nanotube bundles with large surface area (625 m2/g) and aspect ratio (50000:1),” says Thiago Henrique Rodrigues da Cunha, researcher of the Nanomaterials Technology Center (CTNano) of the Brazilian Federal University of Minas Gerais (UFGM) and corresponding author of this paper, which was recently published in the journal Carbon (impact factor 2017 = 7,082).

The method, in addition to generating good quality nanotubes, allows producing relatively large quantities of this material using relatively low amounts of raw materials. “Even using small systems, it is possible to obtain carbon nanotubes at a kilogram/day scale,” says the researcher. As the nanotubes obtained showed a very large ratio between surface area and mass (more than 625 square meters weighing only one gram), the production of nanotubes by this method could reach a few million square meters per day.

With the nanotubes obtained and a type of alcohol, the scientific team prepared a paste which was distributed over filter paper, forming a film that was separated from the paper when the paste dried. The black film was 40 micrometers thick and was flexible and foldable. Macroscopic aggregates of carbon nanotubes like this are commonly called buckypapers.

On the left, carbon nanotube film (buckypaper) produced by the team. On the right, an airplane made with this buckypaper.

“The buckypaper produced from these nanotubes exhibited great surface area and good electrical conductivity, which makes them particularly interesting in the manufacture of electrodes for batteries and supercapacitors,” says Thiago da Cunha, who adds that the CTNano team is already working to use the buckypapers in these energy storage devices. A patent on the process was deposited at the end of 2017. “Our intention is to introduce this technology to potential partners in order to convert it into a high value-added product,” reveals Cunha.

The secret of the process

Scanning electron microscopy image of carbon nanotube bundles that grew from both sides of an aluminum flake.

The CVD nanotube production processes take place inside a tube furnace into which gas containing carbon and catalytic nanoparticles are inserted. Subjected to high temperatures, the gas decomposes, and the carbon atoms deposit on top and around the nanoparticles, forming tubes (the nanotubes). The nanoparticles can be prepared in the same furnace used for nanotube growth.

The secret of the method developed by the Minas Gerais team lies precisely in the preparation of the catalytic nanoparticles. In broad lines, it is a matter of preparing a powder containing iron (Fe) and cobalt (Co) on aluminum flakes (material that had never before been mentioned in the scientific literature as a support for the growth of nanoparticles). The mixture is then subjected to temperatures of 350 to 650 °C for 4 hours, in an atmosphere similar to the air we breathe. This process, known as calcination, produces nanoparticles of iron and/or cobalt oxides. Then, the catalyst nanoparticles, still on the aluminum flakes, are introduced into the CVD furnace, whose internal temperature is brought to 730 °C. The ethylene gas (C2H4) is then introduced, which supplies the carbon so that the nanotubes grow perpendicular to the aluminum flakes.

Scientists observed an interesting advantage of using this new medium. During the calcination, a thin layer of aluminum oxide is formed on the surface of the aluminum that encapsulates the nanoparticles and prevents them from agglomerating or spreading. In addition, in the next step of the process, the aluminum oxide acts as a matrix of the nanotubes, driving their growth in the form of aligned bundles.

To test whether the calcination temperature of the nanoparticles would influence their performance as catalysts, the CTNano team carried out some experiments. The conclusion was that calcination at temperatures of 500-550 °C produces more mixed oxide nanoparticles (containing both iron and cobalt, of the CoFe2O4 formula) and produces better results in the production of nanotubes, both quantitatively (yield) and qualitative (diameter of the nanotubes).

“Unlike other methods described in the literature, which generally display low yield and are dependent on relatively expensive techniques (evaporation, sputtering) for the preparation of the catalyst, we describe in this paper a simple method to produce a catalyst in powder form, which can be used for continuous production of few-walled nanotubes using the chemical vapor deposition technique (CVD),” summarizes Thiago da Cunha.

CTNnano

The work was funded by the Brazilian agencies Fapemig (Minas Gerais State Research Foundation) and CNPq, as well as Petrobras. The work was carried out at CTNano, except for the microscopy images, conducted at the UFMG Microscopy Center.

CTNano emerged in 2010 based on the motivation to develop products, processes and services using carbon nanotubes and graphene, in order to meet industrial demands in line with the training of qualified human resources. The research realized in CTNano has already originated 26 patents and contributed to the development of more than 200 researchers in the area. According to Thiago da Cunha, CTNano will inaugurate, in 2018, its own headquarters with an area of approximately 3,000 m², located in the Technology Park of Belo Horizonte (BH-TEC).

Authors of the paper, from UFMG, except for Viviany Geraldo, who is a professor at the Federal University of Itajubá (UNIFEI).

The “old-fashioned” sewing thread universally used, for example, to sew buttons, has recently been transformed by a Brazilian scientific team into an electrically conductive and multifunctional material. In fact, the various uses of this new sewing thread go far beyond sewing. It works very well as a mini electric heater, as a component of supercapacitors (devices that store and release energy, similar to batteries) and as a bactericidal agent. In addition, the thread is flexible and comfortable to the touch, and retains its electronic properties even after being washed, twisted, curled or folded repeatedly.

With these characteristics, this fiber can play an important role in wearable electronics – the set of electronic devices designed to be worn on the human body, incorporated into clothing or accessories.

“As the thread is a basic element for the design of textiles, we imagine that any wearable product can make use of this technology”, says Helinando Pequeno de Oliveira, a professor at the Brazilian Federal University of the Vale de São Francisco (Univasf) and leader of the scientific team that developed the conductive and bactericidal thread. Together with three other authors, all linked to Univasf, Oliveira authors an article reporting this work, which was recently published in the journal ACS Applied Materials and Interfaces.

The conductive and bactericidal fiber of Oliveira and his collaborators is made of a composite material: cotton thread of 0.5 mm diameter, coated with carbon nanotubes and polypyrrole. The resulting material presents, in addition to high electrical conductivity, good electrochemical activity – necessary characteristic for it to be used in supercapacitors.

To make the conductive fiber, the Univasf team developed a very simple process, formed by two main stages. In the first step, pieces of cotton thread are submerged in a paint of carbon nanotubes, previously modified in order to increase their interaction with the cotton. As a result, the thread is coated by a continuous network of interconnected nanotubes.

The second step is intended to coat the fibers with a second material: polypyrrole. To do this, a solution is initially formed by pyrrole and the solvent hexane, in which the fibers coated with nanotubes are submerged. Thereafter, another solution is poured over this preparation. The second solution consists of water and some compounds, which will be incorporated in very small amounts into the chemical composition of the polypyrrole in a process called “doping” of the material. At the interface between both solutions, which do not mix, the small pyrrole molecules are bound together, resulting in the formation of polypyrrole macromolecules that are deposited on the surface of the fibers. This process, in which a polymer forms at the interface between two solutions, is called “interfacial polymerization”. “Given the good polypyrrole doping level (optimized for this synthesis) and its strong interaction with the functionalized nanotubes, the resulting fibers display excellent electrical properties,” says Professor Oliveira.

The scientific team also produced some variants of this sewing conductive thread. For example, a fiber without carbon nanotubes and another fiber whose polypyrrole coating was produced by means of non-interfacial polymerization. However, the lines with carbon nanotubes and interfacial polymerization showed the best electrical and electrochemical performance.

Heaters and supercapacitors made of cotton fibers

First and second generation supercapacitor prototypes based on conductive sewing lines.

“The high electrical conductivity (together with the good porosity of the material) made of the material a great prototype for application in electrodes of supercapacitors”, says Oliveira. “These properties also made it possible to use it as an electric heater with very low operating voltages (of the order of a few volts). In addition to these applications, the antibacterial potential of the matrix”, he adds.

In addition to testing the performance of the conductive and bactericidal fiber in isolation in the laboratory, Oliveira and his collaborators developed a proof of concept. “We used a needle to sew the thread in a glove”, says the professor. With this we could monitor the temperature that the hand, wearing this glove, would reach when we connected the device to a power supply,” he explains.

The heating system tested on the glove can be adapted to a variety of contexts, such as an ambulatory version of thermotherapy (therapeutic heating of body regions, which is often used in physiotherapy sessions)with the added advantage of antibacterial action. This property is particularly interesting in materials that are used in contact with the skin, since, in this way, they avoid diseases and odors. In the case of polypyrrole, the action occurs when the material electrostatically attracts the bacteria and promotes the breakdown of its cell wall, inhibiting its proliferation.

Local heating (in degrees centigrade) provided by the conductive thread sewn to the index finger of the glove, after applying an electric voltage of 12 V.

A possible wearable product based on the conductive sewing thread is a thermal jacket.It could be powered by a solar cell incorporated into the jacket, or by means of triboelectric devices, which would reap the energy generated by the user’s movement of the jacket.The resulting energy would be stored in a supercapacitor made with the conductive fiber. Tailored to the jacket, the supercapacitor would provide electricity to the heater when needed.
Another example is the energy storage t-shirt, in which Professor Oliveira’s group is currently working to generate a marketable product. We are currently optimizing the production of supercapacitors in pieces of cotton and lycra fabrics as a way to connect them directly to portable power generators, thus enabling the development of energy storage t-shirts,” says Oliveira.

Science and technology developed in the backlands

The work reported in the ACS Appl. Mater. Interfaces and their developments were fully carried out at the Materials Science Research Institute of Univasf, on the campus of the municipality of Juazeiro, located in the north of the state of Bahia. Univasf, which has six campuses located in the interior of the states of Bahia, Pernambuco and Piauí, was created in 2002 and inaugurated in 2004. In the same year, Oliveira became a professor at the institution.

The development of the conductive cotton lines was born from a thread of research on electronics and flexible devices, created in 2016. In 2017, the idea became the theme of the master’s work of Ravi Moreno Araujo Pinheiro Lima, guided by Professor Helinando Oliveira, within the Postgraduate Program in Materials Science at Univasf – Juazeiro, created in 2007. Post-doc José Jarib Alcaraz Espinoza, who was optimizing syntheses of conductive polymers for supercapacitors, adapted a methodology to interfacial polymerization in cotton. With this, the researchers realized that the conductor lines worked as good supercapacitor electrodes, and fabricated these devices. At the same time, with the collaboration of Fernando da Silva Junior, a doctoral student of the institutional postgraduate program Northeast Network of Biotechnology, the team tested the action of the material against the bacterium Staphylococcus aureus, responsible for a series of infections of varying degrees of severity not human.

“These results reflect Brazil’s investment in the internalization of its network of federal teaching and research institutions. With this, the migration of the sertanejo towards the great capitals in the search for knowledge has been reduced. Now there is also more science being produced in the northeastern backlands”, says Professor Oliveira. “However, recent cuts in S & T have launched a huge cloud of uncertainty about the future of science in the country (and in particular about these young institutions). The Brazilian government does not have the right to throw so many dreams in the trash. Science needs to overcome this crisis,” completes the researcher.

Photo of the research group led by Professor Oliveira at the Institute for Research in Materials Science. To the right, in blue, the authors of the article.

Despite all the knowledge on nanotechnology generated over the last few decades, applying nanomaterials to commercial products can still be a difficult task. At the XVI B-MRS Meeting, Professor Pulickel Ajayan, one of the world’s references in nanomaterials and nanostructures, will shed light on this problem. In the plenary lecture he will address in Gramado on the morning of September 14, Ajayan will discuss some challenges of the application of nanomaterials (particularly those of two dimensions) in systems and devices. He will address issues related to the synthesis, characterization and modification of these materials.

Ajayan and his collaborators have developed nanomaterials with diverse functionalities, applicable to fileds such as energy storage and conversion, catalysis, low consumption electronics, nanomedicine or environment care. Among his most famous contributions, are carbon nanotubes filled with molten material acting as nanowire moulds (1993); nanobrushes made of carbon nanotubes, highlighted by Guinness World Records as the smallest ones (2005); the paper battery, made of cellulose and nanotubes (2007); the ultra-dark nanotube carpet, which reflects only 0.045% of light (2008), and a reusable sponge of nanotubes capable of absorbing oil dispersed in water (2012).

Professor and director of the Department of Materials Science and Nanoengineering at Rice University (USA), Ajayan has exceptional publication metrics: a h index of 144 and more than 95,000 citations according to Google Scholar.

Pulickel Madhavapanicker Ajayan was born in 1962 in India, in a small town in the southern state of Kerala. He attended primary school there and then went to the state capital, to a high school that aroused his enthusiasm for learning, his curiosity, and his interest in science.

In 1985, Ajayan graduated in Metallurgical Engineering at Banaras Hindu University (BHU), located in northeastern India and then went on to do a PhD in Materials Science and Engineering at Northwestern University (USA). At that moment, he began to penetrate nanotechnology. In 1989, he defended his PhD thesis about very small gold particles that, some years later, would begin to be called “nanoparticles”.

In 1990, he moved to Japan to pursue a postdoctoral stage at the Fundamental Research Laboratory of the NEC Corporation, where he remained until 1993 in the group that was responsible for a series of seminal studies on carbon nanotubes – including the “discovery” of these nanomaterials, attributed to Sumio Iijima in 1991. During his postdoc, Ajayan obtained important results on the synthesis of nanotubes in large scale and on the filling of nanotubes with other materials.

From Japan, he went to France where he worked as a researcher at the Solid Physics Laboratory of the Université Paris-Sud for two years. Then he went to Germany, where he worked for a year and a half at the Max-Planck-Institut für Metallforschung. In 1997, he moved to the United States to become an assistant professor at the Rensselaer Polytechnic Institute (RPI), the nation’s oldest university of technological research, located in the state of New York. At RPI, he was the Henri Burlage chair Professor in Engineering and worked in the nanotechnology research group.

In 2007, he left RPI and joined the faculty of the Department of Mechanical Engineering and Materials Science at Rice University to be the Benjamin M. and Mary Greenwood Anderson professor of Engineering. In 2014, he also held the founding chair of the Department of Materials Science and NanoEngineering.

Currently, in addition to teaching and leading a research group of about 40 members at Rice University, Ajayan travels a lot, whether to share his knowledge on nanotechnology (he has delivered more than 350 invited lectures and has held visiting professor positions at universities around the world), or to take care of his scientific collaborations. In addition, Ajayan has acted on the boards of several journals, startups and international conferences of the materials and nanotechnology field.

The scientist has received important awards from a number of institutions including the Royal Society of Chemistry (UK), Alexander von Humboldt Foundation (Germany), Materials Research Society (USA), Microscopic Society of America (USA). He also received distinctions of numerous universities around the world, including the doctorate honoris causa by the Université Catholique de Louvain (Belgium). He is an elected member of the Royal Society of Chemistry (UK), American Association for the Advancement of Science (AAAS), and the National Academies of Sciences of India and Mexico, among other scientific societies.

Here follows an interview with the scientist.

B-MRS newsletter: – We would like you to choose some of your contributions to nanotechnology, describe them briefly, and share the paper reference, if possible. Please choose:

– The one(s) you consider to have caused or will cause more social impact.

Pulickel Ajayan: – Several of our discoveries have commercial and social impact. In the past two decades some of the research highlights from our lab have been carbon nanotube arrays as extreme light absorbers (for thermo-photovoltaics), nanotube arrays as gecko-tapes, high conductivity carbon nanotube fibers, graphene oxide membranes for water filtration, carbon nanomaterials for energy storage, light weight polymer nanocomposites, development of two-dimensional materials for electronics and sensors, carbon based quantum dots as catalysis for example CO2 reduction etc.

– The one(s) that gave you more personal satisfaction.

Pulickel Ajayan: – One of the most exciting work was related to the conversion of carbon onions into diamond nanoparticles using electron irradiation. This work was done in collaboration with Prof. Florian Banhart when I was visiting as a post-doc at the Max Planck Institute for Metallforschung in Stuttgart in the mid-90’s. This work published in Nature magazine showed direct observation of graphite to diamond phase transition without application of any external pressure.

B-MRS newsletter: –Have any of your scientific/ technological contributions been transferred to a commercial product? If so, has this transfer occurred through patent licensing, start-up …?

Pulickel Ajayan: – Nanotechnology is a paradigm changing approach on how we will be building materials of the future. It is at the core of bottom-up manufacturing and will impact several areas of future technologies. Our work in the past two decades have focused on creating nano-engineered materials with various types of nanoscale building blocks.

Among the many applications foreseen for carbon nanotubes, there are some nanoelectronic devices that make use of the excellent ability to conduct electricity, through the tiny graphene tubes. For the good performance of nanotubes in some of these applications, the most suitable are the coil configurations, formed by a single nanotube with its two ends free to make contact with other components within a device. Additionally, to not lose conductivity, the nanotube coil should have relatively low density of structural defects.

In practice however, it is not easy for a human being to achieve 1 nm diameter tubes to twist into spiral loops without generating imperfections and leaving their tips separate from the bundle.

Cover of Nano Letters. Representation of a coil formed by a single coiled carbon nanotube. Top right, the insert highlights, through a scanning electron microscopy image, the cross section of a real coil obtained by the team of scientists.

In an article published in the prestigious Nano Letters journal, highlighted in the cover of the April issue of this year, a team of 14 scientists reported the formation of defect-free nanotube coils with free ends, from a spontaneous coiling mechanism of single-wall carbon nanotubes. The study was led by researchers from the Weizmann Institute of Science (Israel) with the participation of four scientists from Brazilian universities (State University of Campinas, Unicamp; Federal University of Minas Gerais, UFMG, and Federal University of Roraima), from ETH Zürich (Switzerland) and from the Bar-Ilan University (Israel).

The team placed iron nanoparticles on silicon dioxide substrates and added a carbon-containing gas – a combination known to promote the growth of long single-wall nanotubes, which can reach more than 100 microns in height. The nanotubes grow perpendicular to the substrate like a forest of trees.

Under these conditions, the scientists created several carbon nanotubes samples, and some were spontaneously coil shaped. The authors analyzed the nanotube coils using SEM, TEM and AFM, obtaining information such as diameter, height and number of coil turns. Using the Raman spectroscopy technique, the authors continued investigating the nanotube coils and found a very low concentration of structural defects and also found that the diameter and chirality of the nanotubes were the same throughout the coil. The Raman spectroscopy analyses were partially carried out at the UFMG by Brazilian Professor Ado Jorio.

To understand the coil formation mechanism, the team used atomistic molecular dynamics simulations, used to depict the physical movements of atoms and molecules. These simulations were headed by Professor Douglas Soares Galvão (Institute of Physics Gleb Wataghin – Unicamp) and carried out by the postdoctoral researcher Leonardo Dantas Machado, former student of Galvão, and by Professor Sergio Benites Legoas (Federal University of Roraima), ex-postdoctoral grant holder in Galvão’s group. At IFGW – Unicamp, Prof. Galvão heads a research group specialized in simulation and computer modeling of nanostructured materials, particularly involving nanowires and nanotubes, and often collaborating with experimental groups from different countries. Through the simulations, the group is able to study, understand and predict phenomena that are sometimes not directly viewed or accessed experimentally in the time scale in which they occur.

Generally speaking, the simulations showed that after growing vertically, the nanotubes that had formed coils began to deposit on the substrate from the bottom up, forming the first turn as a result of their interaction with the carbon gas flow and with the substrate. After this first step, the nanotubes continued to spontaneously and steadily be deposited in a coil-like shape, completing up to 74 turns.

The team also investigated the performance of the coils as inductors (coiled devices that generate magnetic fields when an electrical current passes through, also known as electromagnetic coils) – a nanotube application that had not been studied until now. In the Nano Letters article the nanotube coils showed that despite being highly conductive, they are not yet ready to be used as efficient inductors. However, in the article the analysis of its electrical and magnetic behavior presented new and valuable information which can be used to develop inductive devices from nanotubes.

Cover of Physical Review Letters highlighted in 2013 another article of the international team of scientists, led by Galvão, on carbon nanotube coils.

According to Professor Galvão, the paper published in Nano Letters is a continuation of a previous project on carbon nanotube serpentines that involved his group, the group of Israel, led by Ernesto Joselevich, and Professor Ado Jorio (UFMG). This first study also produced an article featured on the cover of a prestigious journal, the Physical Review Letters (Dynamics of the Formation of Carbon Nanotube Serpentines, L. D. Machado, S. B. Legoas, J. S. Soares, N. Shadmi, A. Jorio, E. Joselevich, and D. S. Galvão, Phys. Rev. Lett. 110, 105502 – Published 8 March 2013).

Galvão recounts that the collaboration between the Brazilians and the Israel group began at a conference in Spain, where he attended a presentation by Joselevich on serpentine-shaped carbon nanotubes. “I believed it was a very interesting problem”, says Galvão. Coincidentally, the two scientists met again in a Brazilian event of condensed matter physics and had lunch together with Ado Jorio. That is when their collaboration began. “From the point of view of simulation, it was a very challenging and difficult project (in addition to specifically developing new protocols for the problem, the simulations involve millions of atoms), but Leonardo and Legoas were able to solve this”, says Galvão.

In addition to being consistent from the scientific point of view, the simulations were interesting from an aesthetic point of view. In this regard, Professor Galvão shares an anecdote. “Joselevich, who is Argentine by birth, knows Brazil and the Brazilian culture quite well. The first time he saw the serpentine simulations, he remembered the melody of “Brasileirinho” (a famous piece of chorinho music). We prepared some video versions incorporating the Brasileirinho as the soundtrack in his honor, jesting with the Brazil-Argentina rivalry, and others with tangos. The Brasileirinho wins, of course”, says the professor jokingly.

Sixteen years ago, working as a post-doctoral fellow at the Massachusetts Institute of Technology (MIT) in the group of professor Mildred Dresselhaus, the Brazilian physicist Ado Jorio de Vasconcelos headed a study that would produce the first successful result of the application of Optics, more precisely Raman spectroscopy, in the individual characterization of carbon nanotubes – keeping in mind that nanotube´s walls are just one atom thick, with diameters typically about one nanometer. In the MIT website, the page of Professor Mildred, who has been studying carbon nanostructures at MIT for more than 50 years, reinforces the importance of the work she has carried out with Jorio: 5 of the 6 publications selected by the emeritus professor are co-authored by Jorio.

When Ado Jorio began his postdoc he was 28 years old and had just finished his doctorate in Physics from the Federal University of Minas Gerais (UFMG). His thesis was on phase transitions in incommensurate systems, conducted under the guidance of Professor Marcos Assunção Pimenta. Prior to that, he earned his bachelor’s degree in Physics, also from UFMG, after studying Electrical Engineering for three years.

After the postdoc at MIT, Jorio returned to UFMG and was later accepted as associate professor of the university in 2002 via a public selection procedure. From 2007 to 2009 he held a position at the Brazilian National Institute of Metrology, Quality and Technology (Inmetro) to develop nanometrology-related activities. In 2010, he became full professor of UFMG and that same year took over the direction of the Coordination of Transfer and Innovation of the University until 2012. In 2013 he was at ETH Zurich (Switzerland) as a visiting professor, carrying out teaching and research activities. In August 2016 he became Dean for Research of UFMG.

Since 2002, Jorio has expanded the subject of his post-doctoral work. He has conducted research in optics and the development of scientific instrumentation, namely the study of carbon nanostructures with various applications. An example of this diversity is a study in which Jorio participates, in which nanotechnology field techniques are used to understand details of the composition of the “Indian black earth”, a highly fertile soil with carbon sequestration potential, which is found in places formerly inhabited by Indians in the Brazilian Amazon.

Jorio holds one of the highest H-index among scientists in Brazil: 74, according to Google Scholar. He is also one of the most cited researchers in the world, evidenced by the inclusion of his name in the latest Thomson Reuters international list, which tabulated 1% of the most frequently cited papers in each knowledge area among all the indexed scientific articles between 2003 and 2013. Jorio is the author of over 180 scientific articles and 20 books or book chapters, and 8 patent applications. According to Google Scholar, his publications combine more than 30,000 citations.

His contributions have received numerous acknowledgments from prestigious institutions, such as the Somiya Award from the International Union of Materials Research Societies in 2009; the ICTP Prize of the Abdus Salam International Centre for Theoretical Physics in 2011, and the Georg Forster Research Award by the Humboldt Foundation in 2015, among many other national and international awards.

In the XV Brazil-MRS (SBPMat) Meeting, Ado Jorio will deliver a plenary lecture on a topic in which he is one of the world’s leading experts, the use of Raman spectroscopy to study carbon nanostructures. The Brazilian scientist will talk about how the technique evolved until reaching the nanoscale. He also promises to reveal some tactics that allow using light, whose wavelength is at least hundreds of nanometers, as a probe to investigate structures of only few nanometers.

See our interview with this member of the Brazilian research community in Materials and plenary speaker at our annual event.

SBPMat Newsletter: – Tell us what led you to become a scientist and work in the Materials area.

Ado Jorio: – It was a winding path! I entered university to study electrical engineering. Back then I played in a progressive rock band, so I looked for scientific research in the area of music. I was told to talk to a teacher at the physics department who enjoyed music, studied acoustics and materials. That’s how my career began and which ended up in materials science.

SBPMat Newsletter: – In your own words, what are your main contributions to the Materials area.

Ado Jorio: – I would say there are two main contributions. The first is in the area of carbon nanotubes, I have shown that optics could be brought to the level of individual nanotubes. This gave way to a very broad research field because there are various types of nanotubes, depending on their diameter and chirality. Before this work, people were studying nanotubes. After this work, people began to study specific types of nanotubes. It would be equivalent to saying that researchers studying the atom then realized that there are different types of atoms. The article that was the linchpin of this discovery was the [PRL86, 1118 (2001)]. The second contribution was the advancement of optics to study carbon nanostructures more broadly. I worked on several fronts, from scientific instrumentation for optical measurements below the diffraction limit, to the study and characterization of defects, approaching materials of interest in soil science, biotechnology and biomedicine. Some key references are the books “Raman Spectroscopy in Graphene Related Systems” and “Bioengineering Applications of Carbon Nanostructures”.

SBPMat Newsletter: – We always invite the interviewee to leave a message for the readers who are beginning their scientific careers. Many of these readers would like to one day achieve an H index like yours. What do you say to them?

Ado Jorio: – Make a big effort to attend conferences and make great presentations, always! Science is a debate and you have to be heard. Never repeat the same presentation. Each public requires a specific focus. Of course this advice depends on funding, but since the beginning of my career I have always spent my own money to fund my travels, and I still do this.

SBPMat Newsletter: – Leave a message or invitation to your plenary lecture for the readers who will participate in the XV Brazil-MRS (SBPMat) Meeting.

Ado Jorio: – After all of the above, and since the title and abstract are available, I can only offer my thanks to those who will honor me with their presence. It will be an honor to have these colleagues in the auditorium.

Nanomaterials may be useful in processes in which one introduces genes (DNA segments) into particular cells in a controlled manner. These processes are called transfections and can be aimed at curing diseases caused by the lack of a certain gene (gene therapy) or obtaining transgenic organisms, to name but a few examples.

In a study conducted in Brazil by a multidisciplinary team, it was tested the efficiency of several nanomaterials in delivering genes into different types of rat and human cells, all considered difficult to be transfected (hard-to-transfect cells).

The study findings were recently published as a communication on the scientific journal Nanoscale and were the subject of patent applications to INPI (Brazilian Patent and Trademark Office).

The research, which was conducted in only six months, counting from the project design to the submission of the article, involved the work of thirteen scientists from the Universidade Federal de Minas Gerais (UFMG), who were organized into a research network in nanobiotechnology initiated in partnership with FAPEMIG (Minas Gerais state research foundation). “The multidisciplinary approach of the group was instrumental in carrying out the work in a short period of time and in order for it to be accepted for publication in Nanoscale”, says Rodrigo Resende, a professor in the UFMG’s Department of Biochemistry and Immunology, and corresponding author of the article published on Nanoscale.

The idea that led to the research came from Fernanda Maria Policarpo Tonelli’s research thesis, conducted with Resende’s supervision in order to obtain her master’s degree in Biochemistry and Immunology. “The work involved spermatogonial stem cells from tilapias (primary culture), which are hard-to-transfect”, says the professor. “In trying to deliver genes of interest to these cells, we noticed that this was a difficult task”, he says. Once the student realized that the use of functionalized multi-walled carbon nanotubes made the process easier, it came up the idea of systematically checking the ability of a series of functionalized nanomaterials to deliver genes to hard-to-transfect cells.

Indeed, nanomaterials are interesting candidates to be gene delivery vehicles, not only by the variety of sizes, shapes and properties that can be obtained by the functionalization and the numerous methods of synthesis, but also because they provide high protection to the gene that they must deliver. “They prevent the deterioration of the nucleic acid during the extra and intracellular trafficking”, says Resende. “In addition, among the nanomaterials, the gold nanorods also provide a very useful feature to the gene delivery: the possibility of photothermal release; i.e., the release of genes can be induced to the nanocomplex with exposure to light at the proper wavelength”, adds the professor.

To conduct the experimental research that led to the article on Nanoscale, Resende and his colleagues manufactured some nanomaterials. Carbon nanotubes, gold nanorods, nanodiamonds and nano-graphene oxide were synthesized at the Nanomaterials Laboratory of the UFMG´s Institute of Exact Sciences and the UFMG´s Cell Signaling and Nanobiotechnology Laboratory, while phosphate nanocomposites were manufactured at the Laboratory of Chemical-Biological Interactions and Animal Reproduction of the Department of Morphology of said university.

Following the above mentioned, all nanomaterials were functionalized; i.e., groups of atoms were added to their surfaces so as to achieve specific chemical properties in the materials. This part of the research and almost all of the subsequent experiments were conducted at the Cell Signaling and Nanobiotechnology Laboratory of the Department of Biochemistry and Immunology and the Cell Biology Laboratory of the Department of Morphology, also at UFMG. The actual functionalization of the nanomaterials was confirmed by Fourier-Transform Near-Infrared (FT-NIR) spectroscopic analyzes, conducted at the Nuclear Technology Development Center, located in the UFMG’s campus. Thanks to the functionalization, the nanomaterials stuck to the DNA containing the gene of interest, forming nanocomplexes.

Then, the scientists exposed to the nanocomplexes the rat and human cells, obtained at laboratories of the UFMG’s departments of Physiology and Pharmacology and of Biochemistry and Immunology.

Finally, the researchers observed, for each material and for each type of cell studied, whether the gene of interest had entered the cell and was conducting its functions at the new address.

Scheme of the main stages of the study. The nanomaterials were functionalized to associate themselves with the plasmid DNA containing the gene of interest (in this case, the gene of the cyan fluorescent protein). The hard-to-transfect cells were then exposed to the nanocomplexes (functionalized nanomaterial – plasmid DNA), and it was observed the fluorescent protein expression.

The results published on Nanoscale show that, in general, the nanomaterials are good vehicles for delivering genes to hard-to-transfect cells, equaling or surpassing, in some cases, the capacity of commercially available reagents. Fact: the synthesis of the nanomaterials costs less than the purchase of some reagents.

In addition, the authors of the communication checked the cytotoxicity of each nanomaterial for each cell studied and were able to determine the relevant cell death rates. The scientists concluded that, in proper concentrations, the nanomaterials studied have low cytotoxicity.

These UFMG team’s findings can now be applied to researches involving gene delivery. “For example, if one wishes to study the function of a particular protein in cardiomyocytes and it is necessary to express this protein in these cells, using functionalized multi-walled carbon nanotubes is more efficient than the lipofection with the Lipofectamine 2000 commercial reagent”, illustrates the Resende.

“As for the slightly more distant applications, it is also a possibility to adapt the methodology aiming at the feasibility of gene therapy and transgenesis mediated by nanomaterials”, continues Resende, who says that his research group is already conducting further studies in vitro and in vivo to develop such applications.

According to Resende, another consequence of the article may arise given the difference in behavior observed in the different cells for different nanomaterials. “This offers the possibility of developing studies on how the delivered genes are internalized by each cell and for what reason there are differences in efficiency observed in our study”, says the professor.

The research was funded by Brazlian agenciesCNPq and APEMIG, the National Institute of Science and Technology in Carbon Nanomaterial and the Nanocell Institute, an independent organization founded by the Professor Rodrigo Resende’s research group, for the promotion of science and education.

Scientists from Brazilian institutions, in collaboration with researchers from Israel, “manipulated” carbon nanotubes of 1 nm diameter deposited on quartz surfaces and analyzed strain and displacements produced by this nanointervention. The team identified some behavior patterns in the nanotubes – quartz system and formulated a mathematical model applicable to systems formed by one- and two-dimensional materials over various substrates. The results of the study were recently published in Nano Letters.

To perform the experiments, the Brazilian investigators used samples idealized and produced in the Weizmann Institute of Science (Israel), in which the nanotubes are serpentine-shaped (composed of parallel segments connected together by U-shaped curves).These samples offered a desirable complexity, fostered by both the nanotubes format and the anisotropic character of quartz, which makes adhesion of nanotubes to the substrate not the same at all points.

In order to “manipulate” the system, the researchers used the tip of an atomic force microscope (AFM) built in the laboratory, which allows to change the position of nanometric particles and even of atoms, and to measure in situ the optical spectrum of nanostructures. In each sample, the tip touched a point of the quartz substrate and pushed toward the nanotube, and then proceeded to the optical analysis.

Before and after nanomanipulation, the scientists analyzed a number of points in the nanotube using the technique of Raman spectroscopy, which provides information about the frequency in which the atoms vibrate in the area being studied. More specifically, researchers focused on the frequency of the “G band”, which is used to infer the strain measurements of a considered point, since changes in the frequency of the “G band” are proportional to changes in strain.

Thus, scientists were able to identify and analyze different behavior of the nanotubes after nanomanipulation; for example, the detachment of the substrate and the intense displacement of a full stretch of the nanotube that had received two manipulations at the same point.

In addition to performing the experimental work, the authors of the article in Nano Letters managed to condense the complexity of behaviors they observed in a mathematical model (an equation) capable of explaining them theoretically and predicting these phenomena in similar systems. “The paper proposes a relatively simple model to describe complex effects of nanostructures adhesion in support media,” says Ado Jório, professor in the Department of Physics of the Federal University of Minas Gerais (UFMG) signing the letter as corresponding author.

The research that led to the Nano Letters article was developed within the master’s, doctoral and postdoctoral work of three authors of the letter, in the context of the Brazilian Network for Research and Instrumentation in Optical Nano-Spectroscopy, a project funded by the National Council for Scientific and Technological Development (CNPq) and coordinated by Ado Jório. “This is the result of a broad scientific instrumentation project, which aims at reaching the level of manipulating nanostructures and measuring, accurately, the effect of this process at the nanoscale,” says Jório.

The figure shows one of the 34serpentine-shaped nanotubes on crystalline quartz substrate studied by the authors of the article. To the left of the reader is the nanotube before manipulation. To the right, following the sequence, the same nanotube after the intervention, with the consequent evident strain. The central segment of the nanotube, where the nanomanipulation occurred, was colorized, the gray scale indicating the frequency of the G band in that place. Finally, farther to the right, the chart displays the frequency of G band measured by Raman spectroscopy in successive points of this nanotube (graphical representation of gray hues): the black circles refer to non-manipulated nanotube and the gray colored circles, to the manipulated ones.